Heavy duty collet operated chuck

ABSTRACT

The disclosure relates to an improved heavy duty lathe chuck provided with radially disposed jaws that are positively connected to an actuating collet and slidably supported in mating radial slots in the body of the chuck.

United States Patent 1 Bennett 3,744,809 [451 July 10,1973

1 1 HEAVY DUTY COLLET OPERATED CHUCK [76] Inventor: Herbert E. Bennett,Route 4,

BeloiLWis, 53511 [22] Filed: Sept. 7, 1971 211 Appl. No.: 178,350

[52] US. Cl. 279/121, 279/1 SJ, 279/51, 279/123 [51] Int. Cl B23b 31/10,B23b 31/20 [58] Field of Search ..279/1S.l, 41, 51, 279/74, 119, 121,123, 50

[56] References Cited UNITED STATES PATENTS 2,749,136 6/1956 Smerz279/50 2,828,536 4/1958 Kaiser 279/123 X Primary Examiner-Francis S.l-lusar Attorney-Armin B. Pagel [5 7] ABSTRACT The disclosure relates toan improved heavy duty lathe chuck provided with radially disposed jawsthat are positively connected to an actuating collet and slidablysupported in mating radial slots in the body of the chuck.

5 Claims, 3 Drawing Figures HEAVY DUTY COLLET OPERATED CHUCK BACKGROUNDOF THE INVENTION 1. Field of the Invention The present invention relatesto lathe chucks and more particularly to an improved heavy duty chuckprovided with radially disposed jaws that are positively connected to anactuating collet and slidably supported in mating radial slots in thebody of the chuck.

2. Brief Description of the Prior Art For many years, collet-type chuckshave been employed on metal working lathes in situations that require aworkpiece to be held accurately in concentric relation to the rotationalaxis of the lathe spindle. Such a chuck typically includes a tubularcollet member divided into several longitudinal segments provided withan external tapered conical surface that mates with a correspondinglytapered internal conical surface in the chuck body or the lathe spindle.By means of an appropriate operating mechanism, the conical colletsection is forced axially into engagement with the mating internalsurface of the chuck body, thereby slightly contracting the colletmember to grip a cylindrical workpiece received in the central colletbore. Alternatively, it is also known to provide the end faces of thecollet segments with either integral or removable jaws so that the chuckcan grip a workpiece larger than the collet bore.

In a conventional collet chuck of the type described above, a key may beprovided to prevent relative rotation between the collet member and thelathe spindle or the chuck body, but the driving torque is essentiallytransmitted to the workpiece through the frictional engagement betweenthe mating tapered surfaces that serve to close the collet. Becausethese tapered surfaces are only in line contact with each other exceptat one specific axial position of the collet, relative slippage canscore and ruin one or both of those surfaces. Similarly, excessive axialclosing force can also damage the chuck by denting or coining one orboth of the tapered collet actuating surfaces along the line of mutualcontact. Furthermore, if the workpiece is held by jaws attached to theends of the collet segments and is of substantially greater diameterthan the tapered collet actuating surfaces, the leverage tending toproduce slippage between the collet actuating surfaces is greater thanthat tending to cause slippage between the jaws and the workpiece. Inview of these considerations, it will therefore be apparent that inheavy machining operations requiring high driving torque, sufficientfrictional engagement to prevent relative slippage between the colletactuating surfaces cannot always be achieved without danger of damagingthose critical surfaces.

SUMMARY OF THE INVENTION A principle object of the present invention isto provide a simple, reliable and highly accurate collet-type lathechuck capable of transmitting high driving torque from a lathe spindleto a chucked workpiece without danger of damaging the mating colletactuating surfaces of the chuck.

Another object of the invention is to provide such a chuck that isrelatively compact in its axial dimensions.

Still another object of the invention is to provide a collet-type chuckcomprising a minimum number of components that can be easilydisassembled and reassembled for cleaning and maintenance purposes.

Yet another object of the invention is to provide the subject chuck withwork holding jaws that can be easily replaced without disassembling thechuck or removing it from the lathe.

Briefly, these and other related objectives are achieved in accordancewith the invention by means of a construction in which a collet-typechuck is provided with a rigid body member adapted to be mounted to alathe spindle in fixed concentric relation thereto. The body memberincludes radial guide slots in its end face that slidably receivecorresponding jaws mounted directly to the corresponding longitudinalcollet segments of a collet member received in a central rearwardlyfacing bore of the body member. External tapered surfaces of the colletsegments mate with a correspondingly tapered conical surface in the bodymember bore; thereby assuring that the collet member and the jaws arealways in absolutely concentric relation to the spindle axis and to theradially disposed jaw guide slots. Because the jaws are slidablyreceived in the radial slots of the body member, the driving torque istransmitted to the workpiece directly through the body member and thejaws; thereby positively preventing the collet member from rotatingrelative to the body member and eliminating the need for excessivecollet actuating forces.

Various means for practicing the invention and other advantages andnovel features thereof will be apparent from the following detaileddescriptions of an illustrative preferred embodiment of the invention,reference being made to the accompanying drawing in which like referencecharacters denote like elements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of acollet-type chuck according to a preferred embodiment of the invention,showing the chuck attached to a lathe spindle;

FIG. 2 is an exploded perspective view of the chuck depicted in FIG. 1;and

FIG. 3 is an enlarged cross-sectional view taken along lines 3-3 of FIG.1.

DESCRIPTION OF THE ILLUSTRATIVE PREFERRED EMBODIMENT The illustrativechuck l0 depicted in the accompanying drawings comprises a one-piecebody member 12 in the form of a cylindrical disk 14 integral with arearwardly facing cylindrical hub 16. As best illustrated in FIG. 3, hub16 is bored to provide a tapered internal conical surface 18 that mateswith the corresponding external taper of a conventional tubular lathespindle 20. Three uniformly spaced mounting bolts 22 extend throughmating holes in the body member and are threaded into flange 24 of thespindle; thus accurately mounting the chuck in concentric coaxialrelation to the spindle axis. Alternatively, the body member can bethreaded directly onto the spindle or mounted thereto by otherconventional means. Beyond tapered surface 18, the bore of the bodymember is provided with a longer and more steeply tapered internalconical surface 26 that extends into the forward disk portion of thatmember in coaxial relation with surface 18 and spindle 20. This taperedbore, in turn, is intersected by three accurately machined symmetricallyspaced radial jaw slots 28 in the face of the body member.

The collet 30 comprises a tubular sleeve 32 integral with an enlargedhead 34 provided with an axial center hole 36 and with a tapered conicalperiphery 38 machined to mate with the internal tapered bore 26 of thebody member. Three symmetrically spaced radial slots 40 extendlongitudinally from the front face of the collet almost to the oppositeend of its tubular sleeve; thus providing the collet head with threesegments 42 supported by the corresponding resilient segments 44 ofsleeve 32.

Each of the three chuck jaws 46 comprises a base member 48 made ofhardened steel and a gripping member 50 that is preferably made of amore easily machinable type of steel or other material. The base membersfit accurately into the corresponding slots 28 in the body member withtongues 52 on the faces of the collet head segments received in closelymating grooves 54 of the respective base members. Bolts 56 attach thebase members 48 to the respective collet head segments 42; therebypreventing relative movement between the base members and theirrespective jaw segments and also retaining those components in assembledrelation to the chuck body member. The gripping members 50 are providedwith integral tongues 58 that mate with corresponding grooves 60 in thebase members. A bolt 62 extends through each gripping member and isthreaded into the respective base member and another bolt 64 extendsthrough both members of each jaw and is threaded into the correspondingcollet head segment. Accordingly, both elements of each jaw are rigidlyattached to the collet, but the gripping members can be replaced byremoving bolts 62 and 64 without detaching the base members from thecollet. Obviously, a onepiece jaw can be substituted for the illustratedtwopiece jaw construction, but only by sacrificing the advantageousfeatures mentioned above.

When the illustrative chuck is fully assembled and is in its opencondition shown in FIG. 3, the conical peripheral surfaces of the collethead segments are located toward the rear of the tapered internal bore26 and the base members 48 of the chuck jaws are seated against therearward surfaces of the corresponding jaw slots 28. With the collet andthe jaws so positioned, the gripping surfaces 66 of the gripping membersare spaced apart sufficiently to receive the particular work piece to bemachined. As is well known in the metal working art, the grippingsurfaces of the chuck jaws are machined in the latheto match the size ofthat specific workpiece; thereby insuring accurate concentricity andallowing the chuck to engage and release the work piece properlynotwithstanding the limited radial jaw movement inherent in acollet-type chuck.

An actuating bar 68 is located within the bore of the tubular lathespindle with its enlarged head 70 adapted I to abut against thecorresponding end of the tubular collet sleeve 32. At its opposite end,the actuating bar is connected to an appropriate operating mechanismsuch as a toggle linkage or an air cylinder, whereby the bar can beurged forcibly toward the lathe chuck from its illustrated retractedposition. The movement of the actuating bar forces collet and chuck jaws46 rigidly attached thereto in the same direction and in a movementrelative to stationary lathe spindle 20 and body member 12. Thus basemembers 48 are displaced from the rearward surfaces of the correspondingjaw slots 28. As such movement of the actuating bar forces the collethead segments into the tapered bore 26, the jaws attached to the collethead segments are obviously moved toward the axis of the chuck butremain in concentric relation thereto. Consequently, chuck jaws 46 moveaxially as well as radially in the corresponding jaw slots 28, andbecause the movements are very small, base members 48 are still retainedin the corresponding jaw slots 28. By virtue of the rugged constructionof the entire chuck and the relatively gradual taper of bore 26, it willbe apparent that the chuck jaws can exert a very powerful grippingaction on the work piece. Because the chuck jaws are slidably receivedin the radial slots 28 in the chuck body, however, very high torque canbe imparted from the lathe spindle to the work piece directly throughthe chuck body and jaws without any danger of rotational slippagebetween the collet member and the chuck body and without sacrificing theaccuracy of the chuck.

The invention has been described with particular reference to anillustrative preferred embodiment thereof but it will be apparent thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinabove and as defined in the appendedclaims.

I claim:

l. A collet operated chuck comprising a. a body member provided with anaxial bore including an internal tapered collet actuating surface,

b. means for rigidly mounting said body member to a rotatable spindle incoaxial relation thereto,

c. a collet member including a plurality of collet segments received insaid axial bore and provided with respective external tapered surfacesthat engage and cooperate with said internal tapered surface of saidbore to effect symmetrical radial contraction of said collet segments inresponse to axial displacement of said collet member in a predetermineddirection relative to said body member,

d. means defining a plurality of radially disposed guide slots in theend face of said body member opposite said spindle and in communicationwith said bore,

e. a plurality of jaws respectively received closely and guidingly insaid guide slots-for radial sliding movement relative to the axis ofsaid body members, and

f. connecting means rigidly connecting each of said jaws to acorresponding one of said collet segments, whereby said axialdisplacement of said collet member effects symmetrical radial movementof said jaws along said guide slots toward the axis of said body member.

2. A chuckaccording to claim 1 in which said collet segments includeforwardly facing surfaces generally parallel to said end face of saidbody member and in which said jaws are provided with rearwardly facingsurfaces engaged respectively with said forwardly facing surfaces ofsaid collet segments, said connecting means comprising bolts extendingthrough mating holes in said jaws and threaded into said collet segmentsto maintain said rearwardly facing surfaces of said jaws in immovableengagement with said forwardly facing surfaces of said collet segments.

3. A chuck according to claim 2 in which said forwardly facing colletsurfaces and said rearwardly facing jaw surfaces define mating tongueand groove joints between said jaws and the corresponding colletsegments, said joints being disposed transversely to the direction ofradial movement of said jaws.

4. A chuck according to claim 1 in which each of said jaws comprises arelatively hard base member slidably of said collet segments and asecond set of bolts rigidly connecting said gripping member to thecorresponding ones of said base members, whereby the removal of saidsecond set of bolts allows said gripping members to be removed from saidchuck without detaching said base members from their respective colletsegments.

1. A collet operated chuck comprising a. a body member provided with anaxial bore including an internal taPered collet actuating surface, b.means for rigidly mounting said body member to a rotatable spindle incoaxial relation thereto, c. a collet member including a plurality ofcollet segments received in said axial bore and provided with respectiveexternal tapered surfaces that engage and cooperate with said internaltapered surface of said bore to effect symmetrical radial contraction ofsaid collet segments in response to axial displacement of said colletmember in a predetermined direction relative to said body member, d.means defining a plurality of radially disposed guide slots in the endface of said body member opposite said spindle and in communication withsaid bore, e. a plurality of jaws respectively received closely andguidingly in said guide slots for radial sliding movement relative tothe axis of said body members, and f. connecting means rigidlyconnecting each of said jaws to a corresponding one of said colletsegments, whereby said axial displacement of said collet member effectssymmetrical radial movement of said jaws along said guide slots towardthe axis of said body member.
 2. A chuck according to claim 1 in whichsaid collet segments include forwardly facing surfaces generallyparallel to said end face of said body member and in which said jaws areprovided with rearwardly facing surfaces engaged respectively with saidforwardly facing surfaces of said collet segments, said connecting meanscomprising bolts extending through mating holes in said jaws andthreaded into said collet segments to maintain said rearwardly facingsurfaces of said jaws in immovable engagement with said forwardly facingsurfaces of said collet segments.
 3. A chuck according to claim 2 inwhich said forwardly facing collet surfaces and said rearwardly facingjaw surfaces define mating tongue and groove joints between said jawsand the corresponding collet segments, said joints being disposedtransversely to the direction of radial movement of said jaws.
 4. Achuck according to claim 1 in which each of said jaws comprises arelatively hard base member slidably received in the corresponding oneof said guide slots in accurately fitting relation thereto and arelatively soft gripping member rigidly attached to said base member andprojecting beyond said end face of said body member.
 5. A chuckaccording to claim 4 in which said connecting means includes a first setof bolts rigidly connecting said base members to the corresponding onesof said collet segments and a second set of bolts rigidly connectingsaid gripping member to the corresponding ones of said base members,whereby the removal of said second set of bolts allows said grippingmembers to be removed from said chuck without detaching said basemembers from their respective collet segments.